1. Field of the Invention
The present invention relates to absorption/isolation of vibrations in internal combustion engines, and is more particularly directed to absorbing/isolating vibrations between a connecting rod/bearing cap assembly or crankshaft main bearing assembly and the crankshaft of an internal combustion engine.
2. Description of the Prior Art
In the conventional multi-piston type internal combustion engine pistons are coupled to a crank shaft by connecting rods to translate the reciprocating motion of the pistons to the rotary motion of the crankshaft. Explosions in the combustion engine create vibrations which are transmitted to the connecting rods and from the connecting rods to the crankshaft to a cylinder block. These vibrations increase in force and frequency in high speed engines.
Conventionally, the connecting rods which house rod bearings are separated from a rod journal by a thin layer of lubricating oil. Similarly, the sides of the connecting rod are bathed in lubricating oil preventing contact with the crankshaft. Because of the relative incompressibility of this oil layer, vibrations are easily transmitted from the connecting rod/bearing assembly to the crankshaft and from the crankshaft to the cylinder block causing maintenance problems and wearing and tearing the engine.
In order to alleviate this problem, prior art engines incorporate various vibration dampening devices. Normally they are attached to the crankshaft at an end opposite a flywheel. The vibration dampeners are normally either viscous filled or a hydraulic paddle wheel type. Often, the engines are provided with one or more balancing shafts (providing the appropriate imbalance) to balance the rotating mass of the engine and reduce engine harmonic vibrations.
However, the vibration dampening devices of the prior art suffer from the drawback that they can not be simply incorporated into conventional internal combustion engine designs, are expensive to manufacture, heavy, bulky, complicated and are located far from a source of the vibrations. Therefore, there is a need for a vibration absorbing/isolating device for an internal combustion engine to alleviate all of the drawbacks of the prior art in a simple, efficient and inexpensive manner.
The present invention provides a vibration dampener arrangement adapted to isolate vibrations between connecting rods and a crankshaft and/or between the crankshaft and a cylinder block of an internal combustion engine and prevent/reduce vibrations from being transmitted to the crankshaft and/or to the cylinder block and, consequently, to remaining portions of a drive train assembly.
An internal combustion engine in accordance with the present invention comprises a crankshaft having at least one rod journal and at least one main journal, a cylinder block rotatably supporting the crankshaft, at least one coupling member rotatably coupled to the crankshaft. The at least one coupling member has an annular, substantially cylindrical inner wall defining a crank bore circumscribing one of the main journals and/or one of the rod journals of the crankshaft. Moreover, the inner wall of the crank bore has at least one substantially annular recessed portion formed therein which is axially spaced from opposite ends of the inner wall. The internal combustion engine of the present invention further comprises a vibration dampener assembly disposed in the at least one recessed portion thereby substantially dampening a transmission of vibrations in the internal combustion engine.
The internal combustion (IC) engine of the present invention includes a cylinder block having a plurality of piston receiving bores for receiving a piston which reciprocates therein. The IC engine further includes a crankshaft having a plurality of rod journals which are rotatably mounted by bearings to the lower ends of connecting rods.
The crankshaft further includes a plurality of main journals adapted for rotatably supporting the crankshaft by the IC engine. The cylinder block further includes a plurality of crankshaft support members each comprising a main bearing portion integrally formed within the engine block, and a main bearing cap. The main bearing cap is connected to the corresponding main bearing portion to circumscribe the main journal of the crankshaft through semi-cylindrical bearing shell. The main bearing portions includes a centrally disposed, semi-cylindrical inner wall adapted for receiving a semi-cylindrical bearing shell which, in turn, receives the upper half of the main journal of the crankshaft. The inner wall of the main bearing portion has two longitudinally opposite ends defining a thickness of the inner wall. The main bearing cap includes a semi-cylindrical inner wall substantially symmetrical to the previously discussed semi-cylindrical inner wall of the main bearing portion. The inner wall of the main bearing cap has two longitudinally opposite ends defining a thickness of the inner wall. Each of the crankshaft support members has a crank bore defined by the inner wall of the main bearing portions and the complementary inner wall of the main bearing cap.
The connecting rod in accordance with the present invention, has a split first end adapted for holding the rod journal of the crankshaft and connecting rod bearing shells, and a second end defining a pin opening provided to receive a piston pin. The first end has a crank bore adapted for receiving the rod journal of the crankshaft and the connecting rod bearing shells, and defined by an annular, substantially cylindrical inner wall. The crank bore of the first end of the connecting rod has two longitudinally opposite ends defining a thickness of the crank bore.
In order to effectively reduce and eliminate the transmission of vibration and its harmonics from the connecting rod to the crankshaft and/or from the crankshaft to the cylinder block, a vibration dampener assembly is disposed between the connecting rod and the crankshaft and/or between the crankshaft and the cylinder block.
The vibration dampener assembly in accordance with the first exemplary embodiment of the present invention comprises a pair of substantially semi-annular recessed portions formed in the inner wall of the main bearing cap, a pair of complementary substantially semi-annular recessed portions formed in the inner wall of the main bearing portion of the crankshaft support member, and two pairs of opposite, semi-annular vibration dampener members each disposed in the semi-annular recessed portions. Moreover, the semi-annular recessed portions are axially spaced from the opposite ends of the inner wall of the main bearing cap, while the semi-annular recessed portions formed in the inner wall of the main bearing cap are axially spaced from the opposite ends of the inner wall of the main bearing portions of the crankshaft support member. Preferably, the recessed portions are substantially equidistantly spaced from the opposite ends of the inner wall of the main bearing cap and opposite ends of the inner wall of the main bearing portions.
Preferably, the two pairs of vibration dampener members together form O-ring-like rings and have substantially circular cross-section. Correspondingly, the semi-annular recessed portions have substantially semi-circular cross-sections substantially complementary to the cross-sections of the vibration dampener members. Further preferably, the vibration dampener members are made of a slippery elastomeric oil resistant rubber-like material.
The vibration dampener assembly in accordance with the second exemplary embodiment of the present invention comprises a substantially semi-annular recessed portion formed in the inner wall of the main bearing cap, a substantially semi-annular recessed portion formed in the inner wall of the main bearing portions of the crankshaft support member, and a pair of opposite, semi-annular vibration dampener members each disposed in the semi-annular recessed portion. Moreover, the semi-annular recessed portion is axially spaced from the opposite ends of the inner wall of the main bearing cap, while the semi-annular recessed portion formed in the inner wall of the main bearing cap is axially spaced from the opposite ends of the inner wall of the main bearing portions of the crankshaft support member. Preferably, the recessed portions are substantially equidistantly spaced from the opposite ends of the inner wall of the main bearing cap and opposite ends of the inner wall of the main bearing portions.
Preferably, the two vibration dampener members together form an O-ring-like member and have substantially circular cross-sections. Correspondingly, the semi-annular recessed portions have substantially semi-circular cross-sections substantially complementary to the cross-section of the vibration dampener members. Further preferably, the vibration dampener members are made of a slippery elastomeric oil resistant rubber-like material.
The vibration dampener arrangement in accordance with the third exemplary embodiment of the present invention comprises a recessed portion formed in the inner wall of the first end of the connecting rod and is axially offset from the opposite ends thereof. A pair of opposite, semi-annular vibration dampener members are disposed within the annular recessed portion in the inner wall of the connecting rod. The vibration dampener member is preferably made of an oil resistant elastomeric rubber-like material.
Alternatively, in accordance with the fourth exemplary embodiment of the present invention, each connecting rod may have two opposite, substantially annular recessed portions formed in an inner wall of the crank opening of the first end and axially offset from opposite side faces thereof. Each of the annular recessed portions is adapted to receive the pair of semi-annular vibration dampener members provided for substantially dampening a transmission of vibrations from the connecting rod to the crankshaft. Preferably, the vibration dampener members are substantially equidistantly spaced (offset) from the opposite side faces of the first end of the connecting rod.
Therefore, the present invention provides a simple and inexpensive vibration dampener arrangement for isolating/reducing the engine vibrations at their source, i.e. between the connecting rods and the crankshaft, before they are transmitted through the crankshaft to the other components of the engine, and between the connecting rod and the cylinder block, and prevent/reduce the vibrations from being transmitted to the crankshaft and/or to the cylinder block and consequently to the remaining portions of the drive train assembly.